The final count
If each day 73 million websites serve the Font Awesome WOFF to an average of a thousand visitors who don’t have these fonts in the browser’s cache, at a 26kB savings on the WOFF, we’ve saved…

Theoretical you could save a few KB's download traffic with optimized forked Fonts, but as millions of sites are using a CDN to deliver Fonts. Most CDN delivered Fonts are already browser cached in your own browser.

Serving fonts that are cached are much faster then downloading your own unique forked Fonts (because not present in browser cache).

I tested it once with Font Awesome.
. Its 88 ms for own Fonts vs 2 ms for Fonts that are already cached (Google fonts, Cloudflare CDN (cdnjs)) etc.